The preset invention relates to an image processing apparatus having an area designation function therein. Such an apparatus for example could be a digital copy machine which can perform different types of image processing for multiple areas specified in an original image.
In general, in digital copy machines, optically read original image data is image processed by electrical signals. Accordingly, digital copy machine can perform editing of the images in a manner that cannot be performed by analog copy machine. For example, an edge emphasis processing with respect to originals which have characters by the edges may performed so that the sharpness of these characters is improved. Smoothing processing may performed with respect to dot originals so that the moire is suppressed, while a digital copy machine can also repeatedly outputs a part of image on an original and also create compound images from a plural number of originals.
Normal image processing is performed uniformly with respect to an entire original which is read. However, special effects and image processing with respect to originals containing both characters and photographs is performed only with respect to certain portions of an original in many cases. When processing of only specified portions of an original is performed, the image processing circuit must be able to recognize the closed area that will become the object of the processing, and the content and type of the image processing to be performed.
For this purpose, Japanese Patent Laid-Open No. 45765-1984 is directed to a device which is an image processing apparatus having an area designation function. In such an image processing apparatus, area identification codes corresponding to the content of image processing are stored in a zone memory for each image element. The area identification codes are either "0" or "1". A first image processing is performed with respect to image data of areas identified as "0" and a second image processing is performed with respect to image data of areas identified as "1". In order to reduce the capacity of the zone memory, small areas of 1 mm.times.1 mm are treated as one image element. The "0" or "1" area identification codes are stored in the zone memory for each 1 mm.times.1 mm image element.
However, a conventional image processing apparatus having an area designation function as described above, has the following problems.
(1) It is necessary to have a large memory to store the area information. This is to say that a large memory is required in order to store the area information for each basic unit comprising a area several pixels by several pixels in area (1 mm.times.1 mm). In addition, it is necessary to have a memory with a capacity proportional to size of the originals which are to be read.
(2) There is a poor accuracy of determining the position of the borders of the areas. This is because the basic unit of several pixels by several pixels (1 mm.times.1 mm) is used to determined the positions of the borders. This is to say that it has not been possible to designate areas using one pixel.
(3) In the case of a plural number of areas, it is not possible to designate different image processing for each area. This is because the area information uses only two values (i.e., a single bit) to identify pieces of information. This is to say that image data of each area for which "0" or "1" is stored has the first or secondary image processing performed. It is not possible to perform a third or more image processing.
If the information for each area has the number increased to two bits, for example, the it would be possible to designate area for which a third image processing is to be performed. However, the information that would have to be stored in the memory would become 2-bits for each area and the information for each of the basic elements would double and this would require double the memory capacity. In general, the designation of different image processing for each area requires a large capacity memory.